High velocity, oxy-fuel (HVOF) coatings are being used or considered for a number of aircraft engine applications (both OEM and overhaul). In most cases, HVOF coatings offer improved coating quality over previous plasma spray or combustion coatings. The superior coating quality is primarily a result of the higher particle velocities achieved with HVOF guns. HVOF coatings provide the following benefits:
Higher density (lower porosity)
Higher hardness
Lower oxide content
Better wear resistance
Higher bond strength
Improved corrosion barrier
Smoother as-sprayed surfaces
The various HVOF guns (JetKote, Diamond Jet, CDS, TopGun and JP-5000) are discussed and compared to other thermal spray processes (conventional combustion powder and wire guns, plasma spray and detonation gun). Special attention is given to the JP-5000, which produces particle velocities which are 1000 fps faster than the other HVOF guns. HVOF coating properties are described and illustrated.
